Perceptual completion experiment - Essay Example

There are other reasons too, like ‘cortical scotoma’. There have been numerous studies on the process of perceptual completion and various theories on how this process occurs have been put forward. The first person to notice the phenomenon of filling-in was the inventor of kaleidoscope, Sir David Brewster in the nineteenth century. In 1832, he wrote, “Though the base of the optic nerve is insensible to light that falls directly upon it, yet it has been made susceptible of receiving luminous impressions from the parts which surround it, and…the spot…in place of being black, has always the same color as the ground” (Crossland and Rubin, 2007).

The phenomenon wasn’t studied for a long time until the twentieth century. In the recent times, however, this phenomenon has been largely studied using something called as ‘artificial scotomas’. V.S. Ramachandran and Richard Gregory developed “artificial scotoma”. In artificial scotoma, a small object such as a small dot is surrounded by a background noise. After steadily looking at the object for some time, the object vanishes in the background noise. (Pessoa & Weerd, 2003) But ‘filling in’ is not only influenced by the area around the blind spot.

It is also influenced by attention and extended distance as shown by Ramachandran. If two orthogonal lines, one black and one white, of equal lengths, are running through the blind spot, you do not see a grayish smear at the centre. Instead, the line on which you focus more is more easily completed by perceptual completion. Now, if, one of the lines is longer, the line that is longer is more easily completed. (Pessoa & Weerd, 2003) Dennett, however, argues that there is no ‘filling-in’ but ‘finding out’.

Dennett argues that our brain simply ignores the blind spot and there is no neural process involved in doing this. He further argues that if brain knows what